This invention relates to a catalyst carrier in the form of solid particles which has excellent properties as a carrier of a catalyst for polymerization of olefins, to a catalyst component produced from the catalyst carrier, and to respective processes for production thereof.
In general, it has been desired that the carrier of a catalyst for polymerization of olefins have the following two properties.
(1) A catalyst obtained by causing a catalytically active component to be supported on a catalyst carrier can exhibit a high activity. PA1 (2) When an olefin is polymerized by the use of a catalyst obtained by causing a catalytically active component to be supported on a catalyst carrier, the resulting polymer is spherical or approximately spherical and also has a high apparent density and good fluidity. PA1 (a) a specific area in a range of 0.1 to 10 m.sup.2 /g, PA1 (b) a void volume formed by the pores of not more than 10,000 A of not more than 0.5 ml/g, PA1 (c) a ratio of the average diameter of the tertiary particles to that of the secondary particles in a range of 50 to 200, and PA1 (d) a ratio of the specific surface area of the carrier to that of a sphere having a diameter corresponding to the particle diameter of the tertiary particles in a range of 1 to 10. PA1 (D) a liquid titanium compound which must contain a halogen in the case where this component is used alone or in combination with the component (F), PA1 (E) a silicon halide compound, and PA1 (F) a polymeric silicone compound having a structural unit represented by the formula ##STR1## wherein R.degree. is a hydrocarbon residue.
A catalyst carrier having the properties specified in (2) above can be said to have good "physical properties."
As the catalysts exhibiting excellent properties for polymerization of olefins, a variety of the so-called Ziegler-type catalysts have hitherto been known. It has also been known that the carriers for a catalyst produced from a magnesium compound such as a magnesium dihalide, a dialkoxymagnesium, magnesium hydroxide, magnesium oxide or a dialkylmagnesium are effective as the carriers for the Ziegler type catalysts.
However, the excellent performance of these conventional magnesium compounds as the catalyst carrier was mainly exhibited with respect to the effect of enhancing the catalytic activity as described in (1) above. The catalyst carriers produced from the conventional magnesium compounds were inadequate with respect to the physical properties of the catalyst as described in (2) above. The reason for this is that the principal objects of the researches on the catalysts for polymerization of olefins and especially on the carriers have been directed toward enhancement of the activities of the catalysts.
The physical properties of the catalyst, however, have very important functions that control the properties of the resulting polymers in the actual polymerization reaction of an olefins such as ethylene or propylene. In the industrial practice of the polymerization reaction of olefins, improvement in physical properties of the catalyst has been needed to obtain polymers having such excellent properties in a stable condition.
Thus, there has been a need for developing a novel catalyst carrier for enhancing activity in the polymerization reaction and also a need for providing a catalyst having excellent physical properties.